The attack was the second time this month that someone was pushed to their death in a New York City subway station. Photograph: Seth Wenig/AP

A woman has been taken into custody over the death of a man pushed in front of a speeding subway train, New York City police said on Saturday.

Detectives questioned the 31-year-old suspect after she "made statements implicating herself" but authorities are not releasing her name until formal charging, NYPD spokesman Paul Browne said in a brief statement. Among other things, investigators were arranging for witnesses to positively identify the woman in custody as the attacker, police said.

Sunando Sen, a 46-year-old Queens resident who was born in India and ran a printing shop, died Thursday night when a woman who had been muttering to herself on a train platform in Queens suddenly knocked him on the tracks as a train entered the station.

The woman fled after the attack. Police released security camera video showing her running from the station.

The attack was the second time this month that someone was pushed to their death in a New York City subway station. A homeless man was arrested in early December and accused of shoving a man in front of a train in Times Square. He is awaiting trial, and claimed he acted in self-defense.

Further details on how police managed to identify the suspect in Sen's death were not immediately available.

Investigators had been following up on tips from people who had seen the security video and were checking homeless shelters and psychiatric units in an attempt to identify the woman.

It was unclear whether she had any connection to Sen. Witnesses told police the two hadn't interacted on the platform as they both waited for the train.